1. Field of The Invention
The present invention relates to method and apparatus relating to spectroscopic analysis, and more in particular to non-invasive spectroscopic method and apparatus for the in-vivo analysis of blood.
2. The Prior Art
Classical absorption spectrophotometers analyze a solution of products in glass cuvettes that are placed between a monochromating light system and a photosensor connected to a reading or recording device. Such measurements necessarily contain two elements, namely one of specific spectro-absorption and the other of optical density. The former varies with the specific wavelengths, while the latter is broad over the entire spectrum. Classical monochromator systems have become increasingly sophisticated in order to achieve the high spectral resolutions required for improved analytical accuracy. However, the costs have risen commensurately with the increases in resolution. Painstaking techniques have been employed by researchers to catalog and identify large numbers of classical chemical constituents to make possible the use of automated analyzing systems. Because freshly drawn blood plasma coagulates very quickly, blood analyses ideally should be completed in a matter of seconds in order to be accurate and to avoid the chemical changes which the blood plasma undergoes with time. Prior art spectroscopic methods for analysis of blood are most often performed in the laboratory subsequent to withdrawal of the blood plasma from the patient, and therefore are unable to be completed in sufficient time to avoid chemical changes in the blood.